Fluid pumps



1968 H. s. B'oTToMs ETAL 3,352,346

FLUID PUMPS Filed April 6, 1966 United States Patent 3,362,346 FLUID PUMPS Harry Simister Bottoms, Olton, Solihull, and Joseph John Righton, Edgbaston, Birmingham, England, assignors to Joseph Lucas (Industries) Limited, Birmingham, England, a British company Filed Apr. 6, 1966, Ser. No. 540,545 3 Claims. (Cl. 103-223) ABSTRACT OF THE DISCLOSURE In a fluid pump there is a pumping member arranged to be driven to pump fluid from an inlet to an outlet, the inlet and outlet having respective non-return valves, and there being a hydraulic accumulator member communicating with the outlet at a position downstream of the non-return valve therein, and a spring acting between the pumping member and the movable member of the hydraulic accumulator.

This invention relates to fluid pumps of the kind suitable for supplying fuel to an internal combustion engine, and comprising driving means which is continuously actuated when the pump is in use, a spring loaded reciprocable pumping member engageable by the driving means, an inlet and an outlet in a body of the pump, nonreturn valves in the inlet and outlet respectively, permitting flow from the inlet to the outlet only the arrangement being such that increasing pressure in the outlet urges the pumping member against the spring away from the driving means to reduce the quantity of fluid delivered to the outlet.

The object of the invention is to provide a fluid pump of the kind specified, in a convenient form.

A fluid pump of the kind specified in which the body I also contains a hydraulic accumulator in communication with the outlet, the accumulator and the pumping member both being biased by common spring means.

Examples of the invention will now be described with reference to the accompanying drawings in which: FIGURE 1 is a diagrammatic cross-sectional view of a pump constructed in accordance with this invention and FIGURE 2 is a similar view of an alternative form.

In the example shown in FIGURE '1 there is provided a fluid pump suitable for supplying liquid fuel to an internal combustion engine, the pump being actuated by a rotatable engine driven came 9 or other suitable device.

The pump has a body 10 in which are formed an inlet 1 1 and an outlet 12, non-return valves 13, 14 being disposed in a passage '15 leading from the inlet 11 and in a passage 16 leading to the outlet 12 respectively. The inlet and outlet passages 15, 16 are in communication with a portion of a chamber in the body 10 which is defined between a pair of flexible diaphragms 17, 18. The edges of these diaphragms 17, '18 are connected to the chamber walls and the mid-regions of the diaphragms are connected together in spaced relationship 'by a part 19 which is of generally frusto-conical shape, the diaphragm's 17, 1-8 and part 19 comprising a pumping member and the part 19 being engageable by a reciproca ble driving member 20 slid'ably mounted in the body 10 and arranged to extend into con-tact with the cam 9. The walls of the portion of the chamber between the two 'di'aphnagms 17, 18 are also generally frusto-conical, the diaphragms differing, in area, so that, as the pumping member is reciprocated by the driving member 20, the volume of the space between the diaphragms 17, 18 varies.

In use, as the pumping member moves towards the end of the chamber through which the driving member 20 extends, the volume of the space between the diaphragms 17, 18 decreases, the volume increasing as it moves in the opposite direction.

The chamber in the body 10 is further divided by a third diaphragm 21 to the mid-region of which is connected a disc-like part 22 movable in the direction of movement of the driving member 20. The third diaphragm 21 forms one wall of an end portion of the chamber which affords communication between the passage 16 leading to the outlet 12, and the outlet itself.

Extending between the disc-like part 22 and the part 19 of the pumping member is a compression spring 23. This spring 23 acts to reduce the volume of the end portion of the chamber defined by the third diaphragm 21, and also to move the two diaphragms 17, 18 towards their positions to maintain minimum volume of the space between them.

The third diaphragm 21 and disc-like part 22 serve as a hydraulic accumulator to reduce pressure fluctuations in the flow to the outlet 12 and the arrangement is such that, in use, if the pressure in the outlet 12 rises beyond a value equivalent to the rating of the spring 23 due to the inability of the engine to consume the fuel at the full delivery rate of the pump, the pumping member will be held out of engagement with the driving member 20, against the action of the spring 23. This is due to the fluid pressures acting on the diaphragms b7,18 resulting in a force equal to that of the spring 23. Thus the rate of delivery of the pump is dependent upon the outlet pressure.

In order to permit free movements of the diaphragms 17, 18 and 21 the portions of the chamber other than those through which fuel flows, are vented to atmosphere through suitage passages 24 in the casing 10.

Referring to FIGURE 2, the diaphragms, in the construction of FIGURE 1 are omitted, and are replaced by pistons 25, 26, the former of these being connected directly to the driving member 27 engageable by the cam '9 and the latter being engageable against a stop 28 in the body 10. A common spring 29 acts between the two pistons and the space between the pistons is in communication through a passage 30 with the inlet 11. In use, increasing pressure in the outlet 12 causes the pistons 25, 26 to move against the spring 29, movement of the piston 25 reducing the delivery.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

1. A fluid pump comprising a body having an inlet and an outlet, non-return valves associated with the inlet and outlet respectively, arranged to permit flow only from the inlet to the outlet, a spring-loaded pumping member, driving means engageable with the pumping member to move it against the spring, and a hydraulic accumulator in the body and in communication with the outlet, said hydraulic accumulator having a movable member, said spring acting against the pumping member and the movable member of the accumulator.

2. A fluid pump comprising a body having an inlet and an outlet, non-return valves associated with the inlet and outlet respectively, arranged only to permit flow from the inlet to the outlet a spring-loaded pumping member comprising a pair of interconnected flexible diaphragms of differing elfective areas, the inlet and the outlet communicating with a space defined between said diaphragms, driving means engageable with the pumping member to move it against the spring, and a hydraulic accumulator in the body and in communication with the outlet, said accumulator having a movable member and said spring acting against the pumping member and the prising a piston slidable in the body, driving means engageable with the pumping member to move it against the spring, and a hydraulic accumulator in the body and in communication with the outlet, said hydraulic accumulator having a movable member said spring acting against the pumping member and the movable member of the accumulator.

4 References Cited I UNITED STATES PATENTS 1,784,706 12/1930 Phillips. 1,840,527 1/1932 Rabezzana 1039X ROBERT M. WALKER, Primary Examiner. 

